A mechanical seal device needs to have a simple construction and be straightforward for assembly/disassembly/inspection because it is applied to a mass-produced or massively processed apparatus such as automobiles or chemical devices. Additionally, a mechanical seal device needs to possess a construction achieving a cost reduction. Also a mechanical seal device needs to be able to prevent a sealed fluid from causing a frictional heat generation on the sliding seal faces of seal rings in order to provide a seal against the sealed fluid like oil or chemical liquid. Being motivated by such a background, there have been recent demands for improvements of the mechanical seal device such as simplification of construction thereof, prevention of heat generation at sliding seal faces, enhancement of seal ability of sliding seal faces, packing, O-rings and the like, and an easy inspection and maintenance.
Primary related art of the present invention is found as a mechanical seal device shown in FIG. 6 (for example, see Japanese Patents Laid-open Publication No. 2000-356270 or U.S. Pat. No. 5,213,340). FIG. 6 is a full sectional view of mechanical seal device 100 mounted to a casing 160. This mechanical seal device 100 is applicable to a shaft seal apparatus of a pump operating on chemical liquid or the like.
First, a construction of the mechanical seal device 100 is briefly described. In FIG. 6, the mechanical seal device 100 is of a cartridge type which enables easy installation thereof to an end face 160A of the casing 160 as well as providing a seal between the casing 160 and a rotary shaft 170 which extends through a bore hole of the casing 160. The mechanical seal device 100 contains a mechanical seal 102 therein as a primary component which consists of a stationary seal ring 103 and a rotary seal ring 110 the former of which is disposed in the inboard A of the casing 160. Other primary components include a casing main body 130 and a sleeve 120 in which the casing main body 130 retains a retainer member 106 for the stationary seal ring 103 as well as the stationary seal ring 103 of the mechanical seal 102 in the outboard B of the casing 160 while the sleeve 120 retains the rotary seal ring 110 of the mechanical seal 102 in the inboard A along the rotary shaft 170.
The rotary seal ring 110 is disposed in the bore hole formed within the inboard A of the casing 160. This rotary seal ring 110 is mounted on one end of a long sleeve 120 in order to be disposed deep inboard of the bore hole of the casing 160, whose inner circumferential surface 120C is fitted to the rotary shaft 170. The other outboard end of the sleeve 120 fits a retainer portion 125 and screw sockets 127 applied thereto secures the sleeve 120 against the rotary shaft 170. The rotary seal ring 110 and the sleeve 120 are connected with each other via a connecting member 129. O-rings 105C, 105C are provided for sealing on the respective fit surfaces between the rotary shaft 170 and the sleeve 120 as well as between the sleeve 120 and the connecting member 129. The sleeve 120 and the connecting member 129 are joined with each other by means of a drive pin 120P in a jointly rotatable manner. Further, the connecting member 129 and the rotary seal ring 110 also are joined with each other in a jointly rotatable manner by means of another drive pin which is disposed on the mating area therebetween, not specified by a reference numeral. O-ring 105B is provided for sealing at the mating surfaces between the connecting member 129 and the rotary seal ring 110.
The stationary seal ring 103, on the other hand, is retained by being securely fitted to a stepped annular surface which is disposed on one end portion of a cylindrical retainer member 106. The retainer member 106 fits the inner diameter surface of the casing main body 130 in freely slidable a manner along the axial direction. A fixture pin 132 which is disposed on the casing main body 130 permits the retainer member 106 to be retained in a non-rotatable manner. A seal for the mating faces between the retainer member 106 and the casing main body 130 is provided by means of O-ring 105A. The other end of the retainer member 106 securely mounts a spring receiving member 107.
The casing main body 130 abuts the end face 160A of the casing 160 and is secured relative to the casing 160 by means of fastening a nut 163A on stud bolts 163 which are disposed on the casing 160. A portion of the side wail of the casing main body 130 defines a stepped face 130A. A spring seating member 112 is mounted on the stepped face 130A by means of set screw members 119. A spring 109 supported by the spring seating member 112 is disposed between the spring seating member 112 and the spring receiving member 107, and provides a resilient urging force to the stationary seal ring 103 via spring receiving member 107 and the retainer member 106. The stationary seal ring 103 being urged by the spring 109 comes into a tight contact with the rotary seal ring 110 for effecting a seal against a sealed fluid. There is an installation groove 112G disposed on the inner circumferential surface of the spring receiving member 112. The installation groove 112G receives a spirally wound gasket 115. Seal face 115B of the gasket 115 comes to a sealing contact with the outer circumferential surface 120B of the sleeve 120.
In order to provide a cooling to the sliding faces of the rotary seal ring 110 and the stationary seal ring 103 in the mechanical seal 102 which is composed of the rotary seal ring 110, stationary seal ring 103 and their affiliated members, a flushing passage 140 is led to the outer circumferential side of the mechanical seal 102 while a quenching passage 141 is led to the inner circumferential side of the mechanical seal 102 in which both passages are configured through holes extending from the outer circumference surface of the casing main body 130 to inner circumferential surface thereof. The flushing passage 140 and the quenching passage 141, respectively, permit a flushing fluid (purified water) V1 and a quenching fluid (purified water) V2 to flow therethrough.
Therefore, the mechanical seal device 100 is so configured that the flushing passage 140 and the quenching passage 141 disposed in the casing main body 130 provide the flushing fluid V1 to the inner circumferential surface of the mechanical seal 102 and the quenching fluid V2 to the outer circumferential surface of the mechanical seal 102, respectively. This configuration finds it difficult that it is hard to provide an effecting cooling to a source of sliding frictional heat, i.e., the relatively opposing sliding faces of the rotary seal ring 103 and the stationary seal ring 103, from the outer circumferential side of a wide surface area. In particular, providing a cooling to the relatively opposing sliding seal faces from the inner circumferential side increases a danger of contaminating oil or chemical fluid located in the outer circumferential side with the quenching fluid. Installing the mechanical seal 102 being composed of quenching passage 140, flushing passage 141, rotary seal ring 110 and stationary seal ring 103 between the axially outboard end portion and inboard end portion of the sleeve 120 necessarily increases a length of the sleeve 120. Disposing the gasket 115 on the outboard end portion of the sleeve 120 and the O-rings 105C, 105C on the inboard end portion makes the sleeve 120 even longer and the sealing arrangement for installing the gasket 115 and O-rings 105A, 105C, 105C becomes complex.
More particularly, the O-rings 105C, 105C which are disposed more inwardly in the inboard A than the mechanical seal 102 are meant to provide a seal to prevent the quenching fluid V2 in the quenching passage 141 from breaking into the inboard A, and also a sealed fluid contained in the bore hole of the casing 160 needs to be blocked from breaking into the quenching passage 141, all of which necessarily increase the dimension as well as the complexity of the seal construction. Additionally, use of gasket 115 necessitates a disposition of a spring seating member 112 protruding from the end face of the casing main body 130 in which securing seal ability of the gasket 115 and the spring seating member 112 makes constructions thereof more complicated. Also the fact that the spring seating member 112 and the stationary seal ring 103 protrude from the both end faces of the mechanical seal device 100 imposes a difficulty on part management and control. Another difficulty is caused by such a construction that the stationary seal ring 103 is urged inwardly into the bore hole of the casing 160 by means of spring 109 and the rotary seal ring 110, on the other hand, is meant to be installed by means of adjusting outwardly the casing main body 130, which makes it difficult to adjust the rotary seal ring 110 and the stationary seal ring 103 as they are being installed.
The present invention is introduced to resolve the above mentioned problems. A primary technical goal which this invention tries to achieve is to provide the sliding seal faces of a mechanical seal with a cooling, cleansing and lubrication effect by means of a quenching fluid. Another goal is to make the construction of mechanical seal device simple and compact. Yet another goal is to make assembly, disassembly and maintenance tasks of the mechanical seal device straightforward.